Adjustable support for pressure fixing rollers



Aug. 30, 1966 O. J. ALBRECHT 3,269,626

ADJUSTABLE SUPPORT FOR PRESSURE FIXING ROLLERS Filed March 27, 1964IMAGE FIX/N6 DA-VELOP/NG .ST/iT/ON STAT/0N CHARGE 57'AT/O/V jazz/672227!0520 J QZZreci' United States Patent 3,269,626 ADJUSTABLE SUPPORT FORPRESSURE FIXING ROLLERS Otto J. Albrecht, Trenton, N..I., assignor toOmnitronics, Inc., Philadelphia, Pa., a corporation of Delaware FiledMar. 27, 1964, Ser. No. 355,400 Claims. (Cl. 226-177) This invention isdirected to an adjustable support for pressure fixing rollers in anelectrostatic printing system, and more particularly to such a supportsystem which provides a permanent, visible record on a flexible tapefrom a temporary but visible image represented by the adherence ofconductive, opaque particles to discretely charged areas on the tape.

The progress of the computer arts has been such that the speed ofcomputer operation now greatly exceeds the rate at which information canbe fed into, and processed out of, the computer. Accordingly substantialefforts have been directed to increasing the eificiency and operatingspeed of those components which feed data into, and read the processeddata out of, the computer itself. One significant improvement has beenthe production of electrostatic recording equipment, in whichinformation is placed on a flexible tape by selectively chargingdifferent areas of the tape. The resultant latent image is renderedvisible by passing the selectively charged tape through a mass ofconductive opaque particles which adhere to the charged areas. Thedeveloped image is permanently fixed by the application of heat,pressure, solvent, or some combination of these or other techniques, toproduce a permanent visible record of the information received from thecomputer or other data source.

Pressure fixing is frequently utilized with electrostatic printingsystems to obviate stickiness or undesired adherence of the tape to thesystem elements, which may be caused by the use of heat and/or solventfixing techniques. However there have been various shortcomings, evenwith pressure fixing systems, such as the need for precise alignmentbetween the spaced-apart rollers which apply the pressure to the inkedtape. The initial roller alignment is frequently lost after some hoursof operation, because of the frequent engagement and disengagement ofthe rollers for loading and unloading the system, together with therelatively high pressure exerted between the rollers. In addition, tapesof different widths have been used in various systems, making itdifficult to obtain a fixing pressure distributed evenly across thetapes of difierent widths.

It is, therefore, a primary object of the present invention to providean improved pressure fixing arrangement in which an even and surealignment between the rollers is provided initially, and is maintainedwith only minimum adjustment thereafter.

Another object of the invention is the provision of such a pressurefixing arrangement in which means are provided for simply and accuratelypresetting the pressure which will be applied to tapes of differentwidths, and distributed uniformly across the tape width.

The foregoing and other objects of the invention are realized, in oneembodiment, by providing a pressure fixing arrangement which includesfirst and second rollers, positioned to either side of the tape path.Also provided is means, which may include a support frame, forsupporting one of the rollers for movement toward and away from theother roller. In accordance with a salient aspect of the presentinvention, such means includes a novel pivot element or shaft of givencross section in a direction substantially normal to the direction ofsuch movement, and a reduced cross section in a direction substantiallyparallel the direction of roller movement. This construction maintainsalignment of the rollers as one roller is brought into engagement withthe other roller. In addition, some give or fiexure is afforded by thepivot element being reduced in cross-section along the direction of suchfiexure. Thus, a good contact between the two rollers is always assured,not only when the equipment is set up during manufacture, but also overthe life of the equipment.

In accordance with another aspect of the invention, resilient biasingmeans may be provided to urge one of the rollers toward the other withthe requisite level of pressure. To accommodate tapes of differentwidths, the biasing means may comprise two separate elements,individually adjustable to correspondingly regulate the pressure appliedacross two portions of one roller. The lateral extent of at least onebiasing element is at least equal to the width of the most narrow tapeto be used in the system, so that the pressure adjustment of the secondbiasing element can be varied with respect to that of the first toproduce an even pressure across the entire tape width.

To enable those skilled in the art to practice the invention, the bestmode contemplated for making and using the invention will now bedescribed in connection with the accompanying drawing, in the severalfigures of which like reference numerals identify like elements, and inwhich:

FIGURE 1 is a block diagram of an electrostatic printing arrangement inwhich the present invention finds utility;

FIGURE 2 is a simplified front view of a pressure fixing arrangementconstructed in accordance with the inventive teaching;

FIGURE 3 is a top view of the embodiment depicted in FIGURE 2;

FIGURE 4 is a partial side view of the structure shown in FIGURES 2 and3, useful in understanding an important aspect of the present invention;and

FIGURES 5 and 6 are illustrative showings, similar to side views of theindicated components, but omitting portions of the support frame 25, forpurposes of clarity in illustrating the flexing action of the outerportions of pivot shaft 26, useful in understanding the operation of thepresent invention.

General system As shown in FIGURE 1, an electrostatic printer 10 may beused to process a blank tape 11 drawn off va supply reel 12, to providea visible and permanent image on the processed tape 13 which is wound ona take-up reel 14. A recorder or printing unit 10 in general comprisesthree sub-assemblies: a charge station 15, in which discrete areas ofthe flexible web are selectively charged to represent an informationpattern; an image developing station 16 in which conductive opaqueparticles are attracted to the charged areas of the tape to develop thelatent information pattern; and an image fixing station 17 in which thetemporarily visible pattern is fixed to produce a permanent record ofthe information originally deposited on the tape at charge station 15.With this general perspective of the system, image fixing station 17will now be considered.

Pressure fixing arrangement As shown in FIGURE 2, a pressure fixingstation 17 is aflixed to a panel 20, which may be a portion of the frontpanel of an electrostatic printer. The fixer arrangement comprises afirst roller 21 journalled on a shaft 22, which extends through panel 20and is mounted in suitable bearings to be driven by a motor (neither thebearings nor the motor are indicated, in that their mounting andoperation are well known) whenever the electrostatic printer isenergized. Accordingly, to fix the temporarily visible image on thetape, it is necessary to force a second roller 23 toward roller 21, toprovide a compressive force of a level sufiicient to effect the pressurefixing operation. Pressure roller 23 is journalled on a shaft 24, in itsturn supported in a first end portion of frame member 25 positionedsubstantially normal to front panel 20. Frame member 25 includes asecond end portion journalled on a shaft or pivot element 26 received inbearings 27 and 28 (FIGURES 36), but the bearing support is omitted tomore clearly portray the inventive structure. A pair of set screws 39are provided to lock shaft 26 tightly to support frame or carrier 25. Itis thus apparent that support frame 25 can pivot about shaft 26,responsive to the selective application and removal of forces to theother end 30 of support frame 25.

A cantilever spring assembly 31 including a pair of bias elements orsprings 32 and a second pair of shorter springs 33 is afiixed by a pairof screws 34 and a fastening plate 35 to end portion 30 of support frame25. A rotatable, generally circular member 36 may be formed as a partof, or mounted on, a shaft 37 which is journalled in bearings (notshown) in front panel 20, to afford angular displacement of member 36responsive to forces selectively ap plied to a handle member 38 aifixedto member 36 by screwing into a correspondingly tapped aperture inmember 36, or afiixed by other suitable means. A pair of adjustingmembers 40 are provided, each of which has a spherical head portion 41and a threaded body portion 42 which is received in a correspondinglytapped bore of member 36. A slot 43 is provided in the upper end of eachmember 40, to permit angular rotation of the member and a correspondinglinear adjustment of the position of head portion 41 with respect to thesurface of spring 32 when member 36 is in the position depicted in FIG-URE 2. A pair of nylon-tipped set screws 29 provide for selectivelocking of adjustment members 40 in position. The entire assembly ofcomponent 36 and its associated elements, together with springs 31affixed to the left end of frame member 25, can be considered as abiasing means for effecting the engagement of pressure roller 23 withmain drive roller 21.

From inspection of FIGURE 2, it will be apparent that upon effectingangular displacement of handle 38 in a clockwise or counter-clockwisedirection, the head portions 41 of adjusting elements 40 will also bedisplaced in a like direction, out of engagement with the surfaces ofsprings 32, to remove the bias force from frame member 25. In a relatedmanner, the compressive force between rollers 23 and 21 can be restoredby displacement of handle 38 in the counterclockwise or clockwisedirection, to again engage extremities 41 with springs 32.

Certain of the components depicted in FIGURE 2 are also shown in FIGURE3. The slots 43 for positioning adjusting members 40 are visible abovethe extensions of leaf spring surfaces 32.

In the right-hand portion of FIGURE 3, support frame 25 is shown to havea pair of support areas or arms 45 and 46 in which the center portion ofshaft 26 is received. The diameter of the center of shaft 26, where itis received in the bores of support portions 45 and 46, is such that theshaft is tightly fitted to support frame 25 and set screws 39 lock theshaft to carrier 25. This construction assures that the rear portion ofsupport frame 25 will always be in precise alignment with the centerportion of shaft 26. Shaft 26 also includes a first outer leg portion47, terminating in an end portion 48 which is received within a bearingmember 28. The bearing support is not indicated in the drawing. In likemanner, the other extremity of shaft 26 includes an outer leg portion 52terminating in a rounded end portion 53, which is received in a bearingunit 27 supported within a bearing support (not shown) in conventionalmanner.

It is noted that outer leg portions 47 and 52 of shaft 26 are ofsubstantially the same cross section as the central portion in a plane,or in a direction, substantially =perpendicular to the direction ofrelative displacement between pressure roller 23 and main drive roller21.

FIGURE 4 illustrates a salient aspect of the present invention,emphasizing the substantially reduced cross section of outer legportions 47 and 52 in a direction substantially parallel the directionof relative displacement between roller 23 and roller 21. By providing asolid central portion on shaft 26 received within bore or hearingportions 45 and 46 of the support frame, support frame 25 is alignedwith the central portion of shaft 26. However, by providing a reducedcross section in outer leg portions 47 and 52 in the direction offlexure of support frame 25, unbalances of fixing pressure and/orsurface irregularities of either roller 23 or 21 which might otherwisecause unsatisfactory operation of the system, are precluded fromadversely affecting the pressure-fixing operation.

The improved operation, and sureness of roller alignment, is bestdescribed in connection with FIGURES 5 and 6. Assuming, for purposes ofexplanation, that main drive roller 21 is out of round, at least alongone surface (as indicated in FIGURE 5 in greatly exaggerated form),without the reduced-section outer legs of this invention, it would beexpected that as pressure roller 23 were displaced into engagement withmain drive roller 21, the left portions would engage and compress thetape therebetween, but effective pressure fixing would not beaccomplished in the right hand portion of this assembly. However, inaccordance with the inventive teaching and as particularly illustratedin FIGURE 6, the reduced crosssection outer legs of shaft 26 give orflex as the rollers are urged into engagement, thus to enable roller 23to be aligned substantially flush with the adjacent surface of maindrive roller 21 and ensure an effective pressure fixing operation acrossthe complete lateral dimension of the tape as it passes between therollers. This improved structure not only minimizes the time and expenserequired to effeet the original alignment of the pressure fixing arrangement, but also provides for a long, trouble-free life of the equipmentwithout constant attention to the critical relationship between thesetwo rollers.

Another important aspect of the present invention is the ease andprecision with which the system is compensated to provide an evenpressure distribution across the width of the tape, especially when thesystem is changed over from operation with tape of a first Width to tapeof a second width. For example, tape widths may vary from one-quarterinch to one and one-quarter inches in the lateral dimension.

Referring again to FIGURE 3, it is noted that the positions of members40 can be adjusted by inserting a screwdriver or similar tool into slots43 and effecting rotation of members 40, to correspondingly vary thelevel of the bias force transmitted over springs 32 to frame 25 androller 23. The alignment means (not shown) for maintaining the tape inthe proper position for fixing retains the tape with the inner tape edgealways at the same position with respect to the front panel 20; suchtape edge is coincident with broken line 60 shown in FIGURE 3. With theillustrated configuration, the upper one of the bias surfaces 32 (FIGURE3) is arranged to transmit a force distributed evenly across thecomplete tape when the tape is of minimum width. The lower adjustingspring 32 is then regulated to provide a bias force which, whendistributed across the remainder of the tape, will provide asubstantially equal compressive force across the remainder of the matingsurfaces between rollers 23 and 21. By way of example, if a tape of oneinch width were used, it is assumed that the three-quarter inch segmentof the tape nearer to front panel 20 would be compressed by the forcetransmitted over upper spring 32. This adjustment is made in the mannerdescribed above, by inserting a tool such as a screwdriver in slot 43and adjusting the position of the upper member 40 to effect therequisite force of a reference level transmitted over upper spring 32. Acorresponding adjustment is then made to effect the transmission of aforce one-third the reference level over the lower one of springs 32, inthat this force will be applied to compress a one-quarter inch width oftape, only a third the lateral extent of the tape compressed by theforce transmitted over the upper one of springs 32.

By readily accommodating tapes of various widths in the pressure fixer,considerable flexibility of this portion of the system is realized, andthere is no restriction imposed on the overall system by theconstruction and operation of the pressure fixing stage.

By way of example, and in no sense by way of limitation, dimensions of apivot element 26 successfully employed in practice of the invention areset out below. The overall shaft length was 2.5", and the center portionof the shaft, including those portions received in support arms 45 and46 of the support frame, was 1.625". The diameter of this center portionof pivot element 26, as well as the generally spherical outer portions48 and 53, was 0.3125". The extent of the reduced cross section outerportions 47 and 52 was 0.150".

While only a particular embodiment of the invention has been describedand illustrated, it is manifest that various modifications andalterations may be made therein. It is, therefore, the intention in theappended claims to cover all such modifications and alterations as mayfall within the true spirit and scope of the invention.

What is claimed is:

1. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is displacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned to one side of the tape path;

a second roller positioned to the other side of the tape path; and

means for supporting one of said rollers for movement toward and awayfrom the other of said rollers, including a shaft element comprising atleast a portion which has a cross section of given dimension in adirection substantially normal to the direction of such movement, and across section smaller than said given dimension in a directionsubstantially parallel to the direction of movement, therebyaccommodating irregularities in the roller surfaces and ensuring uniformpressure application between the rollers to provide uniform fixing ofthe image on the flexible tape.

2. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is displacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned to one side of the tape path;

a second roller positioned to the other side of the tape path; and ameans for supporting one of said rollers for movement toward and awayfrom the other of said rollers, including a pivot element having acentral portion with a cross section of given uniform dimension, and apair of outer portions coaxial with said central portion, each outerportion having a cross section smaller than said given dimension in adirection substantially parallel to the direction of roller movement,

thereby accommodating irregularities in the roller 65 surfaces andensuring uniform pressure application between the rollers to provideuniform fixing of the image on the flexible tape.

3. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is displacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned to one side of the tape path;

a second roller positioned to the other side of the tape path;

0 movement, thereby accommodating irregularities in the roller surfacesand ensuring uniform pressure application between the rollers to provideuniform fixing of the image on the flexible tape.

4. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is diplacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned below the tape path;

a second roller positioned above the tape path;

a support frame, having a first end portion for supporting one of saidrollers for movement toward and away from the other of said rollers, anda second end portion for receiving a pivot element; and

a pivot element having a central portion with a cross section of givenuniform dimension positioned within the second end portion of thesupport frame, a pair of outer portions each with a cross sectionsmaller than said given dimension in a direction substantially parallelto the direction of roller movement, and a pair of generally sphericalbearing portions, one aflixed to the extremity of each outer portion ofthe pivot element, thereby accommodating irregularities in the rollersurfaces and ensuring unifrom pressure application between the rollersto provide uniform fixing of the image on flexible tape.

5. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is displacedalong a given path, a pressurefixing arrangement comprising:

amain drive roller positioned below the tape path;

a pressure roller positioned above the tape path;

a support frame, having a first end portion for supporting the pressureroller for movement toward and away from the main drive roller, and asecond por tion for receiving a pivot element;

first and second bearing supports, each spaced at a distance from, andaligned with, said second end portion of the support frame; and

a pivot element having a central portion with across section of givenuniform dimension positioned within the second end portion of thesupport frame, and

having a pair of outer portions each with a cross section smaller thansaid given dimension in a direction substantially parallel to thedirection of roller movement, each outer portion terminating in agenerally spherical bearing portion which is received in one of saidbearing supports, thereby accommodating irregularities in the rollersurfaces and ensuring uniform pressure application betweenthe rollers toprovide uniform fixing of the image on the flexible tape.

6. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is diplacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned to one side of the tape path;

a second rolled positioned to the other side of the tape path;

means for supporting one of said rollers for movement relative to theother of said rollers, including a pivot element having a cross sectionof given dimension in a direction substantially normal to the directionof such movement, and a cross section smaller than said given dimensionin a direction substantially parallel to the direction of movement; and

resilient biasing means comprising at least two elements, each elementbeing individually adjustable to relative to the other of said rollers,including a pivot element having a cross section of given dimension in adirection substantially normal to the direction of such movement, and across section smaller than said given dimension in a directionsubstantially parallel to the direction of movement;

biasing means comprising first and second resilient elements; and

at least two adjusting elements, one adjusting element positioned toengage the first resilient element and regulate the bias force appliedacross a first lateral portion of the area between the rollers, and theother adjusting element positioned to engage the second resilientelement and regulate the bias force applied across a second lateralportion of the area between the rollers, thereby to provide a uniformfixing pressure for tapes of different widths.

8. In an electrostatic printing system in which a flexible tape havingconductive particles adhering to individually charged areas is displacedalong a given path, a pressurefixing arrangement comprising:

a first roller positioned to one side of the tape path;

a second roller positioned to the other side of the tape path;

means for supporting one of said rollers for movement relative to theother of said rollers, to provide a compressive force along a lateralarea between the rollers; and

a single resilient biasing assembly comprising at least two integralelements, one of said elements being individually adjustable to regulatethe compressive force only across a first portion of the lateral areaand the other of said elements being individually adjustable to regulatethe compressive force. only across the remaining portion of said lateralarea, thereby to provide a uniform fixing pressure for tapes ofdifferent widths.

9. In an electrostatic printing system in which a flexible 8 pressiveforce along a lateral area between the rollers; a single biasingassembly, including first and second integral spring elements,positioned so that the first spring element applies a compressive forceonly regulate the fixing pressure across a portion of the along a firstportion of said lateral area and so that tape, thereby to provide auniform fixing pressure for the second spring element applies acompressive tapes of different widths. force only along the remainingportion of said lateral 7. In an electrostatic printing system in whicha flexible area; tape having conductive particles adhering toindividually at first adjusting means disposed to regulate the forcecharged areas is displaced along a given path, a pressure- 10 applied bythe first spring element; and fiXillg g ment comprising: a secondadjusting means disposed to regulate the force a first Teller Positionedto one side of the p P applied by the second spring element, thus toprovide a second roller positioned to the other side Of the tape auniform fixing pressure across said lateral area as P tapes of difierentwidths are used in the system. means Supporting one Of Said rollersmovement 10. In an electrostatic printing system in which a flexibletape having conductive particles adhering to individually charged areasis displaced along a given path, a pressure-fixing arrangementcomprising:

a first roller positioned to one side of the tape path;

a second roller positioned to the other side of the tape path;

a frame member for supporting one of said rollers for movement relativeto the other of said rollers, to provide a compressive force along alateral area between the rollers; l

a first cantilever type spring having first and second end portions,said first end portion being secured to one end of the frame member;

a second cantilever type spring having first and second end portions,said first end portion being secured to said one end of the framemember;

shaft means having a central body portion spaced from the second endportion of each cantilever type spring; a first adjusting element,having a threaded body portion received in said shaft means and a headportion engaging the second end portion of the first cantilever typespring, the position of the first adjusting element in the shaft meansdetermining the level of the bias force applied over the frame member toa first 40 portion of the lateral area between the rollers;

a second adjusting element, having a threaded body por- References Citedby the Examiner tape having conductive particles adhering toindividually charged areas is displaced along a given path, a pressure-UNITED STATES PATENTS fixing arrangement comprising: 2,998,905 9/ 1961Bieber 226-187 a first roller positioned to one side of the tape ath;3,021,989 2/ 1962 Sellers 226-494 X a second roller positioned to theother side of the tape 3,073,590 1/1963 Romeo et a1 226-487 X path;means for supporting one of said rollers for movement relative to theother of said rollers, to provide a com- M. HENSON WOOD, 1a., PrimaryExaminer.

A, N. KNOWLES, Assistant Examiner.

8. IN AN ELECTROSTATIC PRINTING SYSTEM IN WHICH A FLEXIBLE TAPE HAVINGCONDUCTIVE PARTICLES ADHERING TO INDIVIDUALLY CHARGED AREAS IN DISPLACEDALONG A GIVEN PATH, A PRESSUREFIXING ARRANGEMENT COMPRISING: A FIRSTROLLER POSITIONED TO ONE SIDE OF THE TAPE PATH; A SECOND ROLLERPOSITIONED TO THE OTHER SIDE OF THE TAPE PATH; MEANS FOR SUPPORTING ONEOF SAID ROLLERS FOR MOVEMENT RELATIVE TO THE OTHER OF SAID ROLLERS, TOPROVIDE A COMPRESSIVE FORCE ALONG A LATERAL AREA BETWEEN THE ROLLERS;AND A SINGLE RESILIENT BIASING ASSEMBLY COMPRISING AT LEAST TWO INTEGRALELEMENTS, ONE OF SAID ELEMENTS BEING INDIVIDUALLY ADJUSTABLE TO REGULATETHE COMPRESSIVE FORCE ONLY ACROSS A FIRST PORTION OF THE LATERAL AREAAND THE OTHER OF SAID ELEMENTS BEING INDIVIDUALLY ADJUSTABLE TO REGULATETHE COMPRESSIVE FORCE ONLY ACROSS THE REMAINING PORTION OF SAID LATERALAREA, THEREBY TO PROVIDE A UNIFORM FIXING PRESSURE FOR TAPES OFDIFFERENT WIDTHS.